FIG. 6.

Invasion of T84 cells by the lpp-msbB TKO and msbB SKO mutants of S. enterica serovar Typhimurium. The T84 cells were infected with the lpp-msbB TKO, lpp DKO, and msbB mutants. Likewise, T84 cells were infected with WT S. enterica serovar Typhimurium and the complemented derivatives of the lpp and msbB mutants at an MOI of 10:1 for 1 h. The monolayers were washed and incubated with medium containing gentamicin (100 μg/ml) for 1 h. After incubation, the cells were washed and incubated with fresh medium (without antibiotic) for another 1 h before they were lysed with 0.1% Triton X-100 (46) and different dilutions were plated on MSB agar plates. Three independent experiments were performed in triplicate, and an asterisk indicates statistical significance (P ≤ 0.05, as determined by Student's t test) compared to WT S. enterica serovar Typhimurium. The difference between the lpp DKO and lppDKO (compl) values was also significant. The arithmetic means ± standard deviations are shown. (compl) indicates a complemented strain.